Question

How do you calculate the formal charge of O3?

Answer 1

The formal charge of the ozone molecule is zero. Its Lewis structures do present charge separation.

Explanation:

With simple VSEPR considerations, there are 18 valence electrons to distribute around the 3 oxygen atoms (24 electrons in total; 6 are inner core).

Typically, a Lewis structure of `O=stackrel(ddot)O^(+)-O^(-)`, would be depicted. Going from left `O` to right `O` and including the 2 inner core electrons on each atom, there are 8, 7, and 9 electrons around each oxygen centre, resulting in formal charges of `0`, `+1`, and `-1`, respectively. Of course, I can draw the other resonance structure, but the Lewis structure has the same electronic formulation. The `/_O-O-O` `~=117^@`; this is slightly LESS than the normal `sp_2` bond angle of `120^@`, due to disproportionate influence of the oxygen lone pair, which tends to compress `/_O-O-O`.

Since the central oxygen has 3 regions of electron density, this molecule is bent.